Conditioning processes involved in the following areas will be investigated: (a) Short-term regulation of food intake (and corresponding hedonic effects) by flavor and taste stimuli. Studies of the effects of systematic manipulation of the caloric-metabolic consequences of ingested substances (including liquid meals of fixed and subject-determined volume) of different flavors and tastes on caloric perception, caloric intake, and pleasantness of ingestants are proposed. (b) Appetitive Responses to the presence of food. Studies of salivary and hormonal responses, following exposure to food, as a function of degree of obesity, deprivation, time of day, habitual eating patterns, and palatability (of last meal and of food stimuli) are proposed, (including studies of the conditionability and de-conditionability of appetitive responses). (c) Metabolic-hormonal consequences and "anticipations" of nutrient input. Studies of the temporal relationships between selected secretory responses (block glucose, insulin, glucagon, and free fatty acids) and the parameters of food intake are proposed.